Microwave Safe Combination Changing

Feb. 1, 2008
A very wise man by the name of Rex Parmalee once drilled into my head that 12 (positive openings) is the number of times a combination should be dialed before closing the safe door. This lesson has served me very well over the years, and I stick to it even with direct drive lock changes.

Microwave containers “safes” are very popular in today's marketplace. They are low-cost, compact units which provide a decent amount of fire protected space. These containers are ideal for senior citizens, college students, people who reside in small apartments, or for that matter, anyone with a limited budget or space constraints.

As we will see, the lock and absence of a relocking device are part of the reason these containers meet the pricing point intended. Custom upgradable security modifications to the container can be done, but unless your customer absolutely needs to utilize a container of this size, the cost per cubic inch is astronomical compared to other larger, more secure units in their stock form.

The container I will use for this demonstration is the Gardall MS911 as shown in photograph one. In its factory condition, it has a combination lock in addition to a key lock. The key lock also acts as pseudo handle as it retracts the boltwork when unlocking. These containers are available with an electronic lock as well. Available from almost any locksmith distributor, you can find the correct container and configuration for your customer's needs.

Photo 2 shows the inside of the unit. This particular container comes with a small slide-out plastic pan. Customers like places for small nick-knacks so they don't become lost with bundles of papers. On the bottom floor, there are provisions to bolt the unit down. This adds greatly to the overall security of the container.

With the removal of the inside door plate, the wheelpack and boltwork become visible as shown in photo 3. Its construction is straightforward. Lining up of the gates allows the key-driven fence room to slide in, thus permitting the door to open. As is also shown in the photo, an adhesive label is attached to the door ascertaining to the fire resistance of a container of this type.

As the sales of these types of units multiply, locksmiths will undoubtably be called upon to change the combination for a customer. Whether it be a Gardall unit or another manufacturer's unit, if it has a direct drive lock, it will work in the same way. Key locks will sometimes vary by manufacturer.

Most times if I need to change a key lock , I will try to replace it with a new one. To remove the wheelpack , simply remove the cotter pin and unscrew the dial from the wheel. In photo 4, the wheelpack has been disassembled and laid out in order for inspection. Note: Whenever dissecting a safe lock, lay out all assemblies and sub-assemblies in the order in which they were taken apart.

In photo 5, the wheelpack has been reassembled to provide a better visual representation as to how the direct drive works. Notice that upon rotation of each individual wheel, the fixed nub of the preceding wheel contacts the fixed nub of the next wheel, thereby transferring the rotational motion. In the photo, only one fixed nub is seen on each wheel. The other is on the backside of the pack, and faces the opposite direction. Photo 4 shows both nubs on the wheels.

How do we change the combination if everything is fixed? Note the silver-colored wheen in photo 6. This wheel is the fourth and last number of the combination.

On this wheel is a raised buss. To meet a price point, the raised buss is cast as part of the wheel. This is what must be moved in order to change the combination. But how can we move it if it is cast?

The first step is to remove the raised buss. This can be accomplished by using a bench grinder or your Dremel tool. Even use of a file would work.

Just make sure it's completely removed and there are no sharp edges. Another tech following in your footsteps will be less than pleased after he or she is cut on a burr left by you.

After the cast buss is removed, you must next make the provisions to put one back as a replacement. This is achieved by tapping the holes for a 10-32 screw as shown in photo 7. By pure luck, there is no drilling required to tap for a 10-32.

In photo 8, the red #1 shows a regular untapped hole. The red #2 shows a tapped hole. Next to that is the raised buss which is to be removed, and on the right, is what will take its place when we are finished.

Photo 9 demonstrates the completed version of the new and improved raised buss. While it is possible to simply seek out a small screw and nut from the bottom of your mayonnaise jar full of odds-n-ends then proceed to slap it in, it is your duty as a professional to act as such. Safe work is the last place you should be cutting corners or be in a hurry. By utilizing the largest screw possible, it will not shear or bend as easily. By tapping the hole, you will now be able to jam the nut and lock it into place. My use of a lockwasher amplifies this effect. I also always use Loctite , as is shown. If this lock should fail, it will not be because of a screw coming loose.

By moving the location of the screw and nut, we are now able to change the combination of the container at will. The screw's head being at a different fixed location in relationship to the numbers of the dial results in a virtual “domino effect” when combined with the rest of the fixed nubs on the remaining wheels in the pack. The raised nubs will pick up at different numbers, and the gates will park under the fence at different numbers.

To find the new combination after changing the buss location, simply utilize the correct dialing sequence while watching the wheelpack . Park the gates under the fence and make note of the numbers where you stop and change direction.

Replace the wheelpack in reverse order, and install a new cotter pin. Photo 10 shows the completed reinstallation and the new combination dialed. There is no hurry while performing safe work. The penalty is too high for a careless mistake or a procedure overlooked while watching the clock.